Nuphar lutea ssp. advena is a perennial, rooted aquatic herb; colonial from thick leaf-bearing rhizomes 5-10 cm thick (Flora of North America Editorial Committee, eds. 1993+), rooted in mud.
Leaves emergent, rarely floating or submerged, alternate, leaf stalk oval or round in cross section, interior with numerous small air cavities, blade broad, 12-40 cm long, 7-30 cm wide, bluntly arrow-shaped; tip rounded, base deeply lobed, lobes bluntly triangular, separated by a broad sinus; held erect, raised above water surface.
Flowers yellow, to 10 cm wide, 3-5 cm thick; petals numerous but very small, inconspicuous, secreting nectar; sepals 6, the outer ones green, thick, the inner yellow, with greenish tips, deeply concave, overlapping; forming a round or saucer-shaped flower; stamens spirally arranged, numerous, flattened, elongate; stigmas 14-18, joined into a broad, pale greenish stigmatic disk 1-1.5 cm wide, each stigma represented by a ray-like line; ovary superior 14-18-parted; flowers solitary, erect, raised 3-4 cm above water surface; stigma is receptive before anthers shed pollen and flowers have been shown to require pollination by insects (Lippok et al. 2000); nectar produced by the petals and/or pollen attract the fly, Hilara atra, the water lily bee Halictus nelumbonis and the beetles Donacia piscatrix and D. rufa. Another pollinator is the pollen-collecting sweat bee Lasioglossum nelumbonis, possibly the same as Halictus n. (Lovell 1918; Schneider and Moore 1977; Fern 2004). Apparently the most effective pollinators of Advena are the ones most abundant at a particular site (Lippok et al. 2000); blooms and fruits June-Sept.
Fruit green, a bag-like, leathery berry, broadly oval, 2-5 cm long and wide; seeds numerous, ca 0.3 cm wide (Radford et al. 1968), eaten by waterfowl (Martin et al. 1951).
Wetland status: OBL. Frequency in NYC: Infrequent.
Frequency in NYC: Infrequent.
Habitat: Sunny ponds, sluggish streams, freshwater tidal streams, less than 2 m deep, tolerates partial shade. Sometimes planted in wetland restorations and mitigations.
Notes: Roots and seeds apparently edible; may have medicinal uses (Fern 2004).